(1) Field of the Invention
The invention relates to a granular moving-bed apparatus, and more particularly to a louver-type reactor which is used to remove inflow dusts, multi-contaminants such as H2S, SOx, NOx, HCl, alkali, ammonia, etc.
(2) Description of the Prior Art
In the art of removing particles or multi-contaminants from a gas, a granular moving-bed filter or reactor is usually utilized to achieve so by introducing the contaminated gas to pass through a louver-type reactor which allows granular materials to flow slowly thereinside. The dust-removing mechanism of the louver-type reactor is carried out by sending the contaminated gas into the reactor through a louvered wall, then having the contaminated gas pass through a curtain formed by slow-moving granular materials inside the reactor so as to leave the particles and the multi-contaminants with the granular materials, and finally fleeing the gas with a substantial clean state through another louvered wall of the reactor. In the art, the apparatus described above is called a granular moving-bed apparatus.
Referring to FIG. 1, a schematic view of a conventional granular moving-bed reactor is shown. The reactor 4 includes an inlet louvered wall 41, an outlet louvered wall 42 and a granular path 43 formed in between for flowing the granular materials 2. As shown, the contaminated gas flow 3 is introduced into the reactor 4 through the inlet louvered wall 41, then contacts with the slow-moving granular materials 2 moving slowly along the path 43, and flows out of the reactor 4 from the outlet louvered wall 42 as a filtered gas flow 3′. In both the inlet and outlet louvered walls 41 and 43 as shown, it is noted that each of the side walls 41 and 43 of the reactor 4 is formed as a shutter wall so that a plurality of serial hopper-shaped structures 44 can be obtained. The hopper-shaped structure 44 is profiled by an inlet guide plate 411 of the inlet louvered wall 41 and an outlet guide plate 421 of the outlet louvered wall 42, by which the granular materials can be stacked and move slowly along the path 43 so as to generate an effective filtration curtain for the penetrating gas flow 3 and 3′.
Referring to FIG. 2A and FIG. 2B, computer-simulation results for downstream velocity distributions on selected surfaces of the hopper-shaped structure 44 are shown, in which the inclination θ for both the inlet and outlet guide plates 411 and 421 is 40°, the V symbols the downstream velocity, and the U symbols the lateral velocity. As shown in FIG. 2B, it is easy to see that non-uniform distribution of V exists in all selected horizontal levels a, b, c, d and e.
By realizing the results of FIG. 2B, a schematic view of the flow of the granular materials 2 as shown in FIG. 3 can be obtained. As shown, in each hopper-shaped structure 44, a flowing core zone 21, a quasi-stagnant zone 22 and a stagnant zone 23 are formed. Upon such a granular flow distribution in the hopper-shaped structure 44, it is inevitable that chemical products from reactions or dust from filtration between the granular materials and the contaminated gas flow 3 residue along the inlet and outlet guide plates 411 and 421, and by which problems of corrosion, plaques, stagnant zones and so on can be formed to the side walls 41 and 42.
It is obvious that the aforesaid problems of the reactor 4 are mainly caused by the non-uniform flow distribution in each hopper-shaped structure 44. In the art, to achieve a uniform flow distribution of the granular materials 2 along the granular path 43 of the reactor 4, some efforts have been made to build in various flow-dividing structures into each hopper-shaped structure 44.
One of aforesaid efforts is Germany patent number DE 3830618 A1 by Priefer et al., whose major technique is shown in FIG. 4. Priefer et al. disclose a granular moving-bed apparatus whose hopper structure 44 includes a roof-shaped divider 441 located symmetrically in the granular path 43 to bifurcate the granular flow. In Priefer et al., the inclinations θ of the inlet guide plate 411 and the outlet guide plate 421 and the roof inclination α of the roof-shaped divider 441 are all 45°. A basic assumption to Priefer et al. is that the flow of the granular materials in the granular path will be a perfect flow. Therefore, by arranging the tip 4411 of the roof-shaped divider 411 flush with an image line connecting the lower ends 4110 and 4210 of the inlet guide plate 411 and the outlet guide plate 421, respectively, flux on each flow section of the granular path 43 will be the same so that the uniform flow distribution of the granular materials 2 can be achieved.
Nevertheless, it is well known that the ideal situation does never exist in a real world. Even that a basic model for including in-flow dividers has been taught by Priefer et al., still, a practical and satisfied apparatus can only be achieved on a trial-and-error base. Apparently, the problem yet to be resolved in the art is how an optimal placement of the roof-shaped structure can be determined. Especially, it is obvious that different granular materials will present different properties, flowability for instance, and the filtration results as well. Therefore, unless an answer or a methodology can be provided, or the cost and labor in constructing an efficient granular moving-bed apparatus for air filtration cannot be saved.